Merge Three Sorted strings
Last updated: January 17, 2026
Quick Overview
Given k sorted strings, merge them into a single sorted result.
Expedia
Coding & Algorithms
Software Engineer
Expedia
January 17, 2026Software Engineer
Onsite
Coding & Algorithms
Hard
38
13
1,490 solved
Given k sorted strings, merge them into a single sorted result.
Expedia uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
Key Topics to Cover
Tree structures and recursion
Hash maps and frequency counting
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Data structure selection and trade-offs
Sorting and searching
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- Can you solve this iteratively instead of recursively (or vice versa)?
- What if the input doesn't fit in memory?
- How would you modify your solution to handle streaming input?
- How would you test this solution thoroughly?
Sharpen Your Skills on Codemia
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Practice DSA ProblemsSample Answer
Problem Analysis
To merge k sorted strings into a single sorted result, we can identify that this problem aligns with a priority queue (or min-heap) approach. This is because we need to efficiently extract the smalles...
Approach
- Initialize a Min-Heap: Start by creating a min-heap (priority queue) to keep track of the current smallest characters among the k strings.
- Insert Initial Characters: For each of the k st...
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